"It's dangerous to be an environmental rights defender anywhere in the world these days, but especially in the Philippines", said Eva Kusuma Sundari, a parliamentarian from the Indonesian Democratic Party of Struggle, or P-DIP, on Monday.

According to the Philippine Star, Duterte said the United Nations human rights team should be fed to the crocodiles.

An ugly war has broken out between the Philippines government and the United Nations, with a senior UN official declaring that President Rodrigo Duterte needs to see a psychiatrist.

UN High Commissioner for Human Rights Zeid Ra'ad al-Hussein defended the independence, impartiality and expertise of special rapporteurs in the face of smear and hate campaigns, some involving incitement to violence.

According to Lu Kang, spokesperson of the Ministry of Foreign Affairs, Duterte's leadership in his administration granted him the "approval and extensive support" from the Filipinos. "These attacks cannot go unanswered, the U.N. Human Rights Council must take a position".

While official government data show at least 4,000 deaths in police anti-drug operations since July 2016, human rights groups such as the Philippine Alliance of Human Rights Advocates (PAHRA) estimate that up to 12,000 people could have fallen victim to Duterte's policies.

However, he made it clear his instructions to remain silent were motivated by contempt for the investigators and the authorities they represent. "There will be no occasion to push them to crocodiles", Presidential Spokesperson Harry Roque Jr. said in a press conference.

Lu was asked by the media to comment on UN high commissioner Zeid Ra'ad Al Hussein's comment on Duterte. This accusation follows the statement of several Special Rapporteurs who denounced the army's attacks against the indigenous Lumad peoples in Mindanao.

Since assuming office, Duterte has sought to improve ties with China, long marred by a bitter dispute over the South China Sea, in pursuit of improved economic ties with Asia's largest economy.

The petition, a copy of which was seen by Reuters, suggested Mr Duterte was following through on his threats to destroy a movement he now regards as duplicitous.

The petition included 18 top leaders of the CPP, including founder Jose Maria Sison and peace negotiator Luis Jalandoni, both based in the Netherlands for three decades.

"Duterte is engaged in a wild anti-communist witch hunt under the guise of anti-terrorism", he said.